Black disazo dye.



NITED STATES PATENT OFFICE.

OSKAR KALTVVASSER AND HUGO JAESSGHIN, OF BERLIN, GERMANY, ASSIGNORS TO AOTI'EN-GESELLSOHAFT FUR ANILIN FABRIKATION,

OF SAME PLACE.

BLACK DISAZO DYE.

SPECIFICATION forming part of Letters Patent No. 683,120, dated September 24, 1901.

Application filed July 12, 1901- serial No. 68,000. '(No specimens.)

To aZZ whom it may concern: I

Be it known that we, OSKAR KALTWASSER and HUGO J AESSOHIN, of Berlin, in the Kingdom of Prussia, German Empire, have invented new and useful Improvements in the Production of Mordant-Dyeing Disaz o Coloring-Matter; and we do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to which it appertaius to make and use the same.

We have found that a valuable disazo dyestuif may be produced by first combining 1.8- amidonaphthol-4-sulfonic acid in an acid solution with alpha diazo naphthalene and coupling, further, the monoazo dyestuff thus obtained in an alkaline solution with the diazo compound of 4-chloro-2-amidophenol sulfonic acid. The dyestuff thus produced dyes wool directly from an acid-bath black shades of a rather sufficient fastness, which shades by a subsequent treatment with an alkali-bichromate are deepened and assume at the same time an extraordinary fas'tness to soap and to milling. It is easily to be understood that this property is unexpected and remarkable in a coloring-matter containing two sulfo groups.

For the production of the 4-chloro-2-amidophenol sulfonic acid employed as a dyestufi component we proceed as follows: Twenty-five kilos of 4-chloro-2-nitrophenol are heated with a solution of one hundred kilos of sodium bisulfite and five hundred liters of water in a vessel combined with a reflux-condenser, and the mixture is kept water in the form of shining leaflets.

In order to produce the new disazo dyecarbonate are then added thereto in order to dissolve the monoazo dyestuff thus formed. A diazo solution obtained by treating, 23.5 kilos of the above-mentioned 4-chloro-2-amidophenol sulfonic acid in the well-known way with sixty parts of hydrochloric acid (specific gravity 12 Baum) and seven parts of sodium nitrite is allowed to run thereto, and the mass is stirred for about twelve hours more until the formation of the new disazo dye is completed. The dye is then precipitated by means of common salt, and it is filtered, pressed, and dried. It forms in the dry state a dark powder, hardly soluble in alcohol, eas ily soluble in water, forming dark-blue solu tions. The aqueous solution remains unchanged on the addition of a small quantity of caustic-soda lye; but it is precipitated by an excess of this agent. The dye is likewise precipitated in the form of bluish black flakes by the addition of a mineral acid. It dissolves easily in concentrated sulfuric acid to a dark-blue solution, from which it will readily separate on dilution with ice-water. It produces on WOOl from an acid-bath black shades, which by a subsequent treatment with an alkali-bichromate are deepened and assume at the same time an extraordinary fastness to soap and to milling.

The result is not materially changed if for the above-described 4-chloro-2-amidophenol sulfonic acid the isomeric sulfo-acid is substituted, which may be obtained by introducing one part of 4t-chloro-2-amidophenol into four parts by weight of sulfuric acid monohydrate, heating the mixture gently for some time, and finally pouring it into icewater.

Having thus described our invention and in what manner the same is to be performed, what we claim as new is- The new disazo dye obtained by first combining 1.S-amidonaphthol-4-sulfonic acid in an acid solution with alpha-diazo-n aphthalene and coupling further the monoazo dyestuif thus obtained in an alkaline solution with the diazo compound of a 4-chloro-2-amidophenol sulfonic acid, the dye forming in the dry state a dark powder, hardly soluble in alcohol, easily soluble in water to dark-blue solutions; the aqueous solution remaining unchanged on the addition of a small quantity of caustic-sodalye, but being precipitated by an excess of this agent; the dye being likewise precipitated from its aqueous solution 26 in the form of bluish-black flakes by the addition of mineral acids; dissolving easily in concentrated sulfuric acid to a dark-blue solution, being separated from this solution by dilution with ice-water in the form of bluishblack flakes; producing on wool from an acidbath black shades which by a subsequent treatment with an alkali-bichrornate are deepened and assume at the same time an extraordinary fastness to soap and to milling.

In witness whereof we have hereunto signed our names, this 21st day of June, 1901, in the presence of two subscribing witnesses.

OSKAR KALTWASSER. HUGO JAESSCHIN. Witnesses:

VVOLDEMAR HAUPT, HENRY HASPER. 

